Fix RpcFrontend consensus and history publication

[Amaury Chamayou (achamayou)]

Summary

• publish consensus and history explicitly from NodeState to each RPC frontend
• store the pointers atomically in both RpcFrontend and EndpointRegistry
• load each pointer once per request attempt or endpoint operation, preserving a stable snapshot without adding locks
• handle unpublished consensus safely during role-based redirect resolution
• exercise an EndpointRegistry consensus reader through /tx during concurrent publication
• remove the obsolete RpcFrontend TSAN suppression

Testing

• ninja -C build
• cd build && ./tests.sh --output-on-failure -R '^(frontend_test|node_frontend_test)$'
• cd build-tsan && TSAN_OPTIONS="suppressions=$PWD/../tsan_env_suppressions:halt_on_error=1" ./tests.sh --output-on-failure -R '^frontend_test$'
• scripts/cpp-format-checks.sh
• scripts/includes-checks.sh
• scripts/copyright-checks.sh
• scripts/ascii-checks.sh

Closes #8123

[Copilot]

Pull request overview

Publishes consensus/history from NodeState to RPC frontends and synchronizes request-side access.

Changes:

• Adds atomic frontend pointer publication and null-safe redirects.
• Adds concurrency and unpublished-consensus tests.
• Removes the obsolete TSAN suppression.

Custom instructions used:

• .github/copilot-instructions.md
• .github/instructions/reviewing.instructions.md

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tsan_env_suppressions	Removes the frontend race suppression.
src/node/rpc/test/frontend_test.cpp	Adds publication and redirect regression tests.
src/node/rpc/frontend.h	Implements atomic publication and request-local pointer loads.
src/node/node_state.h	Publishes consensus and history to frontends.
src/enclave/rpc_handler.h	Adds the publication interface.

[Copilot]

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated no new comments.

Suppressed comments (1)

include/ccf/endpoint_registry.h:177

• EndpointRegistry is a public application API, and changing its protected consensus/history members to atomics changes how downstream subclasses can use them (the logging sample in this PR already has to switch to get_consensus()). Repository policy requires user-facing API changes to be recorded in CHANGELOG.md; please add a migration note directing subclasses to the new accessors.

    std::atomic<ccf::kv::Consensus*> consensus{nullptr};
    std::atomic<ccf::kv::TxHistory*> history{nullptr};